1. Field of the Invention
The present invention relates to a security fence employing a fiber optic cable formed in a pattern and to attached to the security fence to monitor the integrity of the fence against intrusion or tampering. More particularly, the present invention relates to a clip for holding portions of the fiber optic cable, so as to securely hold the fiber optic cable into the pattern.
2. Description of the Related Art
Security fences employing a fiber optic cable monitoring scheme are generally known in the background. For example, see applicant's prior application Ser. No. 10/713,425 filed Nov. 17, 2003, entitled “APPARATUS AND METHOD TO DETECT AN INTRUSION POINT ALONG A SECURITY FENCE,” which is herein fully incorporated by reference. Also see U.S. Pat. Nos. 4,275,294; 4,371,869; 4,399,430; 4,450,434; 4,558,308; 4,676,485; 4,680,573; 5,134,386; 5,416,467; 5,592,149; and the assignees prior Korean Patents 1997-0009968, 20-0205489, and 20-0205490.
In the systems known in the background art, a length of fiber optic cable is formed into a pattern, such as a zigzagging pattern. The pattern is attached to an existing barrier type fence, such as a galvanized chain-link fence. The pattern in the fiber optic cable has a weave size and/or shape which is smaller than the size of a human, so that a human cannot pass though the weave pattern without disrupting the fiber optic cable. In other words, a person would need to cut the fiber optic cable or severely distort the cable (e.g. by bending, stretching and/or pinching) to form a hole in the pattern large enough to pass through. Any such cutting or distortion of the fiber optic cable will interrupt or interfere with light passing through the fiber optic cable and will cause an alarm to be raised.
FIG. 1 illustrates a galvanized chain-link fence 10, in accordance with the background art. In FIG. 1, a fiber optic cable 12 is formed into a zigzagging pattern and attached to the barrier fence 10. A plurality of clips 14 hold the fiber optic cable in the zigzagging pattern.
FIG. 2 is a close-up view of the zigzagging pattern of the fiber optic cable 12, with the barrier fence 10 removed for clarity. FIG. 3 is a close-up view of the clip 14, in accordance with the background art. The clip 14 will be described in greater detail with reference to FIGS. 4–6.
The clip 14 is primarily composed a first part 16 and second part 17. The first part 16 (FIG. 4) is a unitary or one-piece part including a disc-shaped portion 18 and a stem portion 20. The first part 16 would have a substantially T-shaped cross section taken along its mid-line, as can be envisioned in FIG. 4.
The second part 17 (FIG. 5) is a unitary part and is generally disc shaped. A centrally located hole 22 is provided to accept the stem portion 20 of the first part 16. An upper perimeter of the second part 17 has a raise edge 24. The raised edge 24 includes first, second, third and fourth channels 25, 26, 27, and 28 passing therethrough.
To form the zigzagging pattern, an installer must connect portions of the fiber optic cable together. As illustrated in FIG. 5, a first section 30 of the fiber optic cable 12 is manually passed through the first and second channels 25 and 26. A second portion 32 of the fiber optic cable 12 is manually passed through the third and fourth channels 27 and 28.
Next, as illustrated in FIG. 6, the stem portion 20 of the first part 16 is manually inserted through the centrally located hole 22 of the second part 17. Finally, an end 23 of the stem portion 22 is deformed or flattened. The deformation of the end 23 of the stem portion 20 may be accomplished by a tool, and would be similar to a riveting of the first part 16 onto the second part 17.